Limitations of Multicomponent Theories in Surface Thermodynamics and Adhesion Science

Multicomponent theories are widely used in the study of surface thermodynamics and adhesion phenomena, and certainly provide a powerful tool to better understand and rationalize the processes involved. Nevertheless, since they are based on strong assumptions about the mathematical description of molecular interactions and postulate also that the properties of a material are fully characterized by a small number of fixed parameters, multicomponent models are necessarily approximate and show a series of limitations that in some cases may yield results of difficult or questionable interpretation. In this review some of the main problems encountered in applying multicomponent theories are illustrated. Experimental and theoretical evidence in the literature is also considered, which could question the appropriateness of the multicomponent approach as a general method for the analysis of this kind of phenomenon.